Hermetic compressor

ABSTRACT

A hermetic compressor includes: a crank shaft rotated by using an axial direction as a rotational axis; a stator rotating the crank shaft; a first bearing penetrated by the crank shaft and rotatably coupled to one side of the crank shaft based on the stator to support one side of the crank shaft when the crank shaft is rotated; a support part having one side provided at the stator and the other side disposed to be adjacent to the other side of the crank shaft, based on the stator; and a second bearing coupled to the other side of the support part and supporting the other side of the crank shaft.

TECHNICAL FIELD

The present invention relates to hermetic compressor and, more particularly, to a hermetic compressor capable of reducing a friction loss of a crank shaft and lengthening a life span of a bearing supporting the crank shaft.

BACKGROUND ART

A general hermetic compressor includes a motor part provided in a hermetic container and generating power and a compression part operating upon receiving power from the motor part. The hermetic compressor may be classified into reciprocating, rotary, vane, and scroll type compressors, or the like, according to how a refrigerant, a compressible fluid, is compressed.

In the hermetic compressor, a crank shaft coupled to a rotor of the motor part transfers power while rotating together with the rotor, and an interworking member coupled to the crank shaft, receiving power from the motor part, forms a compression chamber to compress a refrigerant.

In the hermetic compressor, oil is filled at a lower portion of a hermetic container, an oil flow path is formed in a penetrative manner in the crank shaft in an axial direction of the crank shaft, and an oil feeder is installed to be immersed in the oil at a lower end of the oil flow path.

Accordingly, when compressor operates, the crank shaft rotates to generate centrifugal force to pump oil, and the pumped oil is sucked to be supplied between the crank shaft and the bearing to thus prevent a friction loss generated when the crank shaft is rotated.

Here, the compression part transfers reaction force according to a reaction to the crank shaft in one direction, and a plurality of bearings penetrated by the crank shaft transfer reaction force in different directions according to their penetrated positions. Here, the crank shaft is bent due to resultant force of the reaction forces.

Also, when a plurality of bearings are installed to be adjacent to prevent the crank shaft from being bent, the behavior of the crank shaft may be stabilized, but a friction loss is increased due to an increase in the area of the bearings according to the increase in the number of bearings, and a life span of the bearings is shortened according to the positions of the bearings.

The increase in the friction loss and the shortened life span of the bearings will result in reduction in the efficiency of the compressor and reduction in the duration of replacement of the bearings.

TECHNICAL PROBLEM

It is, therefore, a hermetic compressor according to the present invention has one or more effects as follows.

TECHNICAL SOLUTION

First, when the crank shaft rotates, the second bearing supports the other side of the crank shaft, making forces acting on the crank shaft balanced.

Second, since the second bearing is coupled to the other side of the crank shaft, force applied to the crank shaft is reduced in a state in which moment balance and force equilibrium of the crank shaft are maintained, the friction loss between the crank shaft and the second bearing is reduced owing to the reduced force, thus increasing compression efficiency and lengthening a life span of the first and second bearings.

Third, since the second bearing is disposed at the other side based on the moment center of the crank shaft to make a moment balance, force of the first bearing supporting the crank shaft is reduced, and accordingly, friction loss between the first bearing and one side of the crank shaft is reduced.

Fourth, since the first bearing is provided at the crank shaft, it supports one side of the crank shaft when the crank shaft is rotated, preventing the crank shaft penetrating the frame from being approached to either side of the frame.

Fifth, since one side of the support portion and the other side of the stator are detachably coupled by a fastening unit, the second bearing can be detachably attached along with the support portion at the other side of the crank shaft.

ADVANTAGEOUS EFFECTS

The effects of the present invention are not limited to the foregoing effects and any other unmentioned effects could be clearly understood by a skilled person in the art from the description of claims.

DESCRIPTION OF DRAWINGS

The above and other objects and features of the present invention will become apparent from the following description of preferred embodiments given in conjunction with the accompanying drawings, in which:

FIG. 1 is a sectional view of a hermetic compressor according to an embodiment of the present invention:

FIG. 2 is a view showing only major components of FIG. 1:

FIG. 3 is a view schematically showing forces acting on a crank shaft according to one embodiment of the present invention: and

FIG. 4 is a view schematically showing forces acting on a crank shaft according to another embodiment of the present invention.

BEST MODE

Advantages and features of the present invention, and implementation methods thereof will be clarified through following embodiments described with reference to the accompanying drawings. The present invention may, however, be embodied in different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the present invention to those skilled in the art. Further, the present invention is only defined by scopes of claims. Like reference numerals refer to like elements throughout.

The hermetic compressor according to embodiments of the present invention will now be described with reference to the accompanying drawings. In the following description, usage of suffixes such as ‘module’, ‘part’ or ‘unit’ used for referring to elements is given merely to facilitate explanation of the present invention, without having any significant meaning by itself.

FIG. 1 is a sectional view of a hermetic compressor according to an embodiment of the present invention.

With reference to FIG. 1, the hermetic compressor according to an embodiment of the present invention includes a hermetic container 1, a motor part 10 rotated in one direction or in both directions, and a compression part 20 installed at an upper side of the of the motor part 10 and compressing a refrigerant upon receiving rotary force from the motor part 10.

The motor part 10 may be configured as a motor that makes a constant velocity rotation in one direction. Also, a regular speed motor or an inverter motor available for a forward rotation and a reverse rotation may be applied as the motor part.

The motor part 10 includes a stator 11 supported by a frame 30 within the hermetic container 1, a rotor 12 rotatably installed at an inner side of the stator 11, and a crank shaft 133 coupled to the center of the rotor 12 to transfer rotary force to the compression part 20.

A sleeve 24 (to be described) is coupled to an upper end of the crank shaft 13 to make a piston 22 reciprocally move. A pin part 13 a is formed to be eccentric to have a certain eccentric amount at the center of the shaft.

An oil flow passage 13 b is formed to penetrate in an axial direction from a lower end of the crank shaft 13 to an upper end of the pin part 13 a. An oil feeder 13 c for pumping oil of the hermetic container 1 is installed at a lower end of the foil flow path 13 b such that it is immersed in oil of the hermetic container 1. An eccentric mass part 13 d having a fan-like shape is formed at a portion where the pin part 13 a, which corresponds to an upper portion thereof, starts, to cancel out an eccentric load while forming a plane of the axial directional bearing 50 with an upper face of the frame 30 (to be described).

The frame 30 is provided between the compression part 20 and the motor part 10. The crank shaft 13 penetrates the frame 30. A through tunnel is formed at the center of the frame 30 to allow the crank shaft 13 to penetrate therein, and the crank shaft 13 penetrates through the through tunnel. A cylinder 21 (to be described) is provided at one side of the frame 30.

A thrust bearing (not shown) may be provided between the frame 30 and the eccentric mass part 131 d according to an embodiment of the present invention. The thrust bearing supports the eccentric mass part to make the crank shaft 13 and the eccentric mass part 13 d rotate smoothly. Oil sucked through the oil flow path 13 b is supplied as a lubricant to the thrust bearing to allow the thrust bearing to rotate smoothly.

A first bearing 40 is provided at one side of the crank shaft 13, supporting one side of the crank shaft 13. The first bearing 40 may be provided between the crank shaft 13 and the frame 30. The first bearing 40 is disposed in the through tunnel and penetrated by the crank shaft 13, and supports the crank shaft 13 to ensure a smooth rotation between the frame 30 and the crank shaft 13. Oil sucked from the oil feeder 13 c may be supplied to the first bearing 40. The supplied oil lubricates the first bearing 40.

A second bearing 60 is disposed at a lower end, i.e., the other side of the crank, and allowing the crank shaft 13 to penetrate therein. The second bearing 60 may be coupled to a support 60 supportedly coupled to the stator 11. These components will be described in detail with reference to FIG. 2 later.

The compression part 20 includes a cylinder 21 forming a certain compression space V1, a piston 22 making a reciprocal movement in a radius direction within the compression space V1 of the cylinder 21 to compress a refrigerant, a connecting rod 23 having one end rotatably coupled to the piston 22 and the other end rotatably coupled to the pin part 13 of the crank shaft 13 to convert a rotational movement of the motor part 10 into a linear movement of the piston 22, a sleeve 24 inserted between the pin part 13 a of the crank shaft 13 and the connecting rod 23 and serving as a friction reduction member, a valve assembly 25 coupled to a front end of the cylinder 21 and having a suction valve and a discharge valve, a suction muffler 26 coupled to a suction side of the valve assembly 25, a discharge cover 27 coupled to accommodate a discharge side of the valve assembly 25, and a discharge muffler communicating with the discharge cover 25 and damping discharge noise of a discharged refrigerant.

The operation of the hermetic compressor having the foregoing configuration according to an embodiment of the present invention will now be described. First, when power is applied to the stator 11 of the motor part 10, the rotor 12 is rotated together with the crank shaft 13 according to interaction force of the stator 11 and the rotor 12.

When the crank shaft 13 is rotated, the connecting rod 23 connected to the pin part 13 of the crank shaft 13 with the sleeve 24 interposed therebetween makes a rotating movement, and the piston 22 coupled to the connecting rod 23 makes a reciprocal movement linearly in the compression space V1 of the cylinder 21 to compress the refrigerant, and this sequential process is repeatedly performed.

At this time, the oil feeder 13 c installed at the lower end of the oil flow path 13 b of the crank shaft 13 pumps oil of the hermetic container 1, and the pumped oil is sucked through the oil flow path 13 b, so that one portion of the pumped oil is supplied to a sliding portion of the compression part 20 and another portion of the pumped oil is supplied between the frame 30 and the crank shaft 13 to lubricate them.

FIG. 2 is a view showing only major components of FIG. 1, and FIG. 3 is a view schematically showing forces acting on the crank shaft 13.

With reference to FIGS. 2 and 3, the hermetic compressor according to an embodiment of the present invention includes the crank shaft 13 rotated by using an axial direction as a rotational axis, the stator 11 installed within the hermetic container and rotating the crank shaft 13, the first bearing 40 penetrated by the crank shaft 13 and rotatably coupled to one side of the crank shaft 13 based on the stator 11 to support one side of the crank shaft 13 when the crank shaft 13 is rotated, a support part 50 having one side provided at the stator 11 and the other side disposed to be adjacent to the other side of the crank shaft 13 based on the stator 11, and a second bearing 60 penetrated by the crank shaft 13 and having one side coupled to the other side of the support part 50 and the other side rotatably coupled to the other side of the crank shaft 13 to support the other side of the crank shaft 13 when the crank shaft 13 is rotated.

The crank shaft 13 is rotated by using an axial direction as a rotational axis. The crank shaft 13 is rotated by using an axial direction of X-X′ line of FIG. 2 connecting the upper and lower ends, as a rotational axis.

The first bearing 40 is disposed between the crank shaft 13 and the frame 30. The first bearing 40 is penetrated by the crank shaft 13 and supports the crank shaft 13 to ensure a smooth rotation between the through tunnel of the frame 30 and the crank shaft 13. The oil sucked from the oil feeder 13 may be supplied to the first bearing 40, and the supplied oil is supplied to the first bearing 40 to lubricate it.

In this case, the first bearing 40 is rotatably coupled to one side of the crank shaft 13, i.e., an upper side of the crank shaft 13, based on the stator 11. Namely, the compression part 20 is disposed at an upper side based on the stator 11, and the oil is disposed at a lower side of the stator 11. Based on the stator 11, the side where the compression part 200 is disposed at one side of the crank shaft 13, and the side where the oil is disposed is the other side of the crank shaft 13. Here, the first bearing 40 is disposed at one side of the cranks shaft 13.

Reaction force according to action and reaction acting on the compression part 20 acts on the crank shaft 13, the first bearing 40 supports one side of the crank shaft 13. The first bearing 40 supports one side of the crank shaft 13 when the crank shaft 13 is rotated, so that the crank shaft 13 may not be inclined to either side of the frame 30 in its rotation.

The stator 11 is disposed at a lower side of the first bearing 40. As described above, the stator 11 rotates the crank shaft 13 along with the rotor 12 upon receiving power.

The support part 50 is disposed at a lower side of the stator 11, i.e., the other side of the stator 11, based on the stator 11. The support part 50 is disposed between the other side of the crank shaft 13 and the other side of the stator 11, such that the second bearing 60 (to be described) is fixed to the stator 11.

One side of the support part 50 is provided at the stator 11. One side of the support part 50 may be integrally formed with the stator 11 according to an embodiment. Also, the support part 50 may be fixed to the stator 11 by a fastening unit 51 penetrating one side of the support part 50 according to a different embodiment. Also, the support part 50 may be coupled to the stator 11 through welding, or the like.

Hereinafter, it is described that the support part 50 is fixed to the stator 11 by the fastening unit 51 penetrating one side of the support part 50, but the configuration of the support part 50 and the stator 11 is not limited thereto. The fastening unit 51 fastened to the stator 11 may be implemented by a general long bolt.

Since one side of the support part 50 and the other side of the stator 11 are detachably coupled by the fastening unit 51, the second bearing 60 (to be described) can be detachably attached along with the support part 50 at the other side of the crank shaft 13.

The other side of the support part 50 is disposed to be adjacent to the other side of the crank shaft 13. Namely, the other side of the support part 50 is disposed to be adjacent to the other side of the crank shaft 13, i.e., the lower side of the crank shaft 13, based on the stator 11. The other side of the support part 50 may be disposed to be spaced apart from the other side of the crank shaft 13 such that the second bearing 60 (to be described) can be coupled.

The crank shaft 13 penetrates the second bearing 600. The second bearing 60 is rotatably coupled to the other side of the crank shaft 13. The second bearing 60 may be press-fit in a space formed by the other side of the support part 50 and the other side of the crank shaft 13 so as to be coupled. In this case, the crank shaft 13 penetrates the center of the second bearing 60.

The support part 50 supports an outer side of the second bearing 60 coupled to the other side of the crank shaft 13, and the second bearing 60 fixed to the support part 50 supports the other side of the crank shaft 133 when the crank shaft 13 is rotated.

The second bearing 60 may be implemented by various bearings such as a rolling bearing, a sliding bearing, and the like. Hereinafter, the second bearing 60 is implemented by a ball bearing, a type of a rolling bearing, but the embodiment of the second bearing 60 is not limited thereto.

The second bearing 60 supports the other side of the crank shaft 13. The second bearing 60 supports the other side of the crank shaft 13 when the crank shaft 13 is rotated, to making forces acting on the crank shaft 133 balanced.

The second bearing 60 makes force acting on the crank shaft 13 balanced in the compression part in which a refrigerant is compressed, upon receiving force of the first bearing acting on the crank shaft 13 and rotary force of the crank shaft 13 at an end portion of one side, i.e., an upper side of the crank shaft 13. In this case, the respective forces acting on the crank shaft 13 must be balanced, and these forces will now be described with reference to FIG. 3.

With reference to FIG. 3, vector R1 represents a force of the first bearing 40 supporting the crank shaft 13, among the forces acting on the crank shaft 13.

Meanwhile, the compression part 20 applies a reaction force F to one end portion of the crank shaft 13. The reaction force F acts on the crank shaft 13 in a direction opposite to the direction of the vector R1.

The second bearing 60 provides a force supporting the crank shaft 133 to the other side of the crank shaft 13, and a vector thereof is R2, which has the same direction as that of F and acts in a direction opposite to the direction of R1.

Here, in order to make the forces balanced to prevent the crank shaft 13 from moving in both directions, the sum of all of the forces must be ΣF=0. Namely, when the direction of R1 is determined to be a positive (+) direction, R1+(−R2)+(−F)=0.

Here, R1=F+R2 and the average F of the forces acting on one end portion of the crank shaft 13 in the compression part 20 is constant, so when R2 is reduced, R1 will be reduced, reducing the force supported by the first bearing 40. As the force supported by the first bearing 40 is reduced, a friction loss between the first bearing 40 and one side of the crank shaft 13 is reduced, enhancing compression efficiency.

Thus, it is required to be designed such that R2 is small, and in order to reduce R2, a moment balance must be considered. In moment balance, the center (O) of moment is positioned on the crank shaft 13 in an axial direction. The center (O) of moment positioned on the crank shaft 13 in the axial direction is positioned at an upper side of the support part 50.

The center (O) of moment of the crank shaft 13 is positioned as one point at one side of the crank shaft 13 supported by the first bearing 40, and the crank shaft 133 makes a seasaw movement based on the center (O) of moment.

Namely, the crank shaft 13 may be rotated in a clockwise direction or counterclockwise direction based on the moment center (O) to generate vibration. In this case, another rotational shaft may be formed to be perpendicular to the rotational shaft X-X′ of the crank shaft 13 penetrating the movement center (O). The crank shaft 13 may be rotated in a clockwise direction or counterclockwise direction based on the another rotational shaft.

Here, in order for the crank shaft 13 to make a moment balance, rather than making a seasaw movement, the sum of all the moments must be ΣM=0. Namely, in order for the crank shaft 13 to be stopped, rather than making a seasaw movement, according to the moment by the force applied to one side of the crank shaft 13 and the force applied to the other side of the crank shaft 13, the sum of all the moments must be 0.

Here, the point supporting the crank shaft 13 by the first bearing 40 is the moment center (O) making a seasaw movement. Here, the vector R1 acting on the first bearing 40 makes a force acting on the moment center (O) , and the moment is R1*0=0.

The reaction force F applied by the compression part 20 to one end portion of the crank shaft 13 is applied to one side, i.e., an upper side, based on the moment center (O), and the moment from the moment center (O) to an operational point on which the reaction force F acts is L1*F and the direction is a positive (+) direction in a counterclockwise direction.

The force provided by the second bearing 60 to the other side, i.e., a lower side, of the moment center (O), is R2, and R2 forms a moment−(L2*R2) in the clockwise direction.

Accordingly, the equilibrium equation with respect to the sum of the moments is +(L1*F)−(L2*R2)=0. Here, R2=(L1/L2)*F, and since F has a certain size as an average force provided to the crank shaft 13 in the compression part 20, and as a result, when L2 is increased, R2 is reduced.

Thus, in order to reduce R2, L2 must be increased, and it is to be disposed at a point farthest from the moment center (O) to the maximum, and in this case, the second bearing 60 must be disposed at the other side of the crank shaft 13.

Namely, the second bearing 60 must be disposed at the opposite side of one end portion on which F acts based on the moment center (O). In this case, the second bearing 60 is disposed at the other side of the crank shaft 13 farthest from F based on the moment center (O) of the crank shaft 13.

Since the second bearing 60 is coupled to the other side of the crank shaft 13, force applied to the other side of the crank shaft 13 is reduced in a state in which the crank shaft 13 is maintained in the moment balance and force equilibrium, and a friction loss between the crank shaft 13 and the second bearing 60 is reduced, thus increasing the compression efficiency and lengthening a life span of the first bearing 40 and the second bearing 60.

FIG. 4 is a view schematically showing forces acting on a crank shaft according to another embodiment of the present invention.

With reference to FIG. 4, a formation of a moment center (O′) of the crank shaft 13 at an upper side of the first bearing 40, rather than at a support portion of the first baring 40, due to a change in the design of the crank shaft 13 or a change in other components will be described, but such a description may also be applicable to a case in which the moment center (O′) is formed at a lower side of the first bearing 40.

As shown in FIG. 4, the first bearing 40 is disposed at one side, i.e., an upper side, of the crank shaft 13 based on the stator 11, and the second bearing 60 is disposed at the other side, i.e., a lower side, of the crank shaft 13 based on the stator 11.

Namely, in spite of the configuration illustrated in FIG. 4, the respective forces acting on the crank shaft 13 must be balanced likewise as in the foregoing embodiment. Among the forces acting on the crank shaft 13, the vector of force supporting the crank shaft 13 by the first bearing 40 is R1.

Meanwhile, the compression part 20 applies reaction force F to one end portion of the crank shaft 13. The reaction force F is the same vector as that of R1, which acts on the crank shaft 13 in a direction opposite to the direction of R1.

The FIG. 4 is a view schematically showing forces acting on a crank shaft according to another embodiment of the present invention.

The second bearing 60 provides a force supporting the crank shaft 13 to the other side, i.e., the lower side, of the crank shaft 13, and the vector is R2 which has the same direction as that of F2 and acts in a direction opposite to that of R1. Here, in order for the crank shaft 13 to make the force balanced, rather than being moved in both directions, the sum of all the forces must be ΣF=0. Namely, when the direction of R1 is determined to be a positive (+) direction, R1+(−R2)+(−F)=0.

Here, likewise as in the embodiment described above with reference to FIG. 3, R1=F+R2 and the average force F acting on one end portion of the crank shaft 13 in the compression part 20 is constant. Thus, when R2 is reduced, R1 will be reduced, reducing the force supported by the first bearing 400.

Referring to the moment sum, the size of moment formed by the first bearing 40 is R1*A, the product of the support force R1 of the first bearing 40 and the distance A between the support point of the first bearing 40 and the moment center (O′), and its direction is a positive (+) direction in a counterclockwise direction.

The reaction force F applied by the compression part 20 to one end portion of the crank shaft 13 is applied to one side, i.e., an upper side, based on the moment center (O′), and the moment from the moment center (O′) to an operational point on which the reaction force F acts is L1*F and the direction is a positive (+) direction in a counterclockwise direction.

The force R2 provided by the second bearing 60 to the other side, i.e., a lower side, of the moment center (O′) forms a moment−(B*R2) in the clockwise direction.

Accordingly, the equilibrium equation with respect to the sum of the moments is +(R1*A)+(L*F)−(B*R2)=0. Here, R2*B=(L*F)+(R1*A), and since L*F is constant in a state in which O′ is not changed, it is determined by (R1*A) and (R2*B).

Here, R1=F+R2, and when it is applied to the above equation, R2*(B−A)=F(L+A)

Here, F and L are constant, so if R2 is to be reduced, A must be reduced in a state in which B is constant, or B must be increased in a state in which A is constant. In this case, A is a support point of the first bearing 40, which is restrained by the coupling of the first bearing 40 to the frame 30, having a small change width in size in terms of design, so increasing B is free in terms of design.

Thus, in order to reduce R2, B must be increased, and here, the second bearing 600 is disposed at the other side of the crank shaft 13 farthest from the moment center (O′) to the maximum in order to increase B. This case is the same as the embodiment described above with reference to FIG. 3.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention. Thus, it is intended that the present invention covers the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents. 

1. A hermetic compressor comprising: a crank shaft rotated by using an axial direction as a rotational axis; a stator rotating the crank shaft; a first bearing penetrated by the crank shaft and rotatably coupled to one side of the crank shaft based on the stator; a support part having one side provided at the stator and the other side disposed to be adjacent to the other side of the crank shaft, based on the stator; and a second bearing coupled to the support part and supporting the other side of the crank shaft.
 2. The hermetic compressor of claim 1, further comprising: a frame in which the crank shaft penetrates, wherein the first bearing is provided between the frame and the crank shaft.
 3. The hermetic compressor of claim 2, wherein the first bearing support one side of the crank shaft when the crank shaft is rotated.
 4. The hermetic compressor of claim 1, wherein the second bearing supports the other side of the crank shaft when the crank shaft is rotated.
 5. The hermetic compressor of claim 1, wherein the support part fixes the second bearing to the stator.
 6. The hermetic compressor of claim 1, wherein one side of the support part is fixed to the stator by a fastening unit penetrating one side of the support part.
 7. The hermetic compressor of claim 1, wherein the support part is integrally formed with the stator.
 8. The hermetic compressor of claim 1, wherein a moment center of the crank shaft is positioned at a support portion of the first bearing supporting the crank shaft in an axial direction of the crank shaft, and a compression part for compressing a refrigerant upon receiving rotary force of the crank shaft is provided at one end portion of the crank shaft based on the moment center of the crank shaft.
 9. The hermetic compressor of claim 8, wherein the second bearing is disposed at the other side based on the moment center of the crank shaft.
 10. The hermetic compressor of claim 1, wherein the second bearing is penetrated by the crank shaft.
 11. The hermetic compressor of claim 1, wherein the second bearing is a rolling bearing.
 12. The hermetic compressor of claim 1, wherein the support part supports an outer side of the second bearing.
 13. The hermetic compressor of claim 1, wherein the second bearing is provided at the other side of the support part.
 14. The hermetic compressor of claim 1, wherein the second bearing is press-fit to a space formed by the other side of the support part and the other side of the crank shaft.
 15. A hermetic compressor comprising: a crank shaft rotated by using an axial direction as a rotational axis; a stator rotating the crank shaft; a first bearing penetrated by the crank shaft and supporting one side of the crank shaft when the crank shaft is rotated; a second bearing penetrated by the crank shaft and supporting the other side of the crank shaft when the crank shaft is rotated; and a support part provided at the stator to fix the second bearing.
 16. The hermetic compressor of claim 15, wherein the first bearing is rotatably coupled to one side of the crank shaft based on the stator.
 17. The hermetic compressor of claim 16, further comprising: a frame in which the crank shaft penetrates, wherein the first bearing is provided between the frame and the crank shaft.
 18. The hermetic compressor of claim 16, wherein the support part having one side provided at the stator and the other side disposed to be adjacent to the other side of the crank shaft based on the stator.
 19. The hermetic compressor of claim 18, wherein the second bearing is penetrated by the crank shaft and has one side coupled to the other side of the support part, so as to be rotatably coupled to the other side of the crank shaft.
 20. The hermetic compressor of claim 18, wherein one side of the support part is fixed to the stator by a fastening unit penetrating one side of the support part. 